Damage to large vehicle entry doors has long been a problem for fleet operators and building owners. Often, large vehicle entry doors are not positioned in full open or full closed positions. Either to conserve energy or for convenience, doors are adjusted to various heights for differing vehicles as they pass through door openings. As a result, vehicles frequently collide with entry doors causing extensive damage to the door, door frame, vehicle or a combination thereof. Additional problems are encountered when a door or frame is damaged to such an extent as to prevent continued operation. If the door cannot be closed after being damaged, continued energy loss and increased security risks ar confronted. If the door cannot be opened, substantial interference with business traffic and increased safety risks are confronted.
Problems are also encountered when a vehicle is damaged extensively by a door collision. Damage to a truck's container can cause the truck to be removed from service for a substantial time period burdening its owner with repair costs and lost earnings.
Furthermore, personal injury can occur. People, passing through partially opened doors, can misjudge door clearances and incur injury. Such injuries are usually to the head and can be serious.
Damage to the door can occur even when a door is opened to its full height because operators of vehicles are not warned of the clearance available for entry. Additionally, doors might appear to be opened to their full height when in reality they are partially closed.
Two reasons for the problems as defined above are one, there is no way for a vehicle driver to determine the height position of the door opening or the door's maximum clearance and two, door operators are not able to accurately judge a door's opening clearance and are not instructed otherwise.
Existing height measuring systems are employed in other areas but do not address the problems as defined above. For example, various highway bridges usually display clearance heights for truck operators. There, the bridge clearance is fixed. There is no continuous adjustment to height as found with a large vehicle entry door.
In the marine environment, ruled marks are incorporated to indicate water an estimated depth or bridge clearance. There, variable depth or height is encountered but of a different nature. Variation in depth is encountered with the slow accumulation of sludge or other debris on the marine floor. The height variation in the marine environment is due to tidal changes which are slow and predictable. Marine operators who are concerned with depth or height clearances calculate ahead of time and need not be concerned with unknown clearances. That situation is not encountered with large vehicle entry doors. There, door heights are continuously adjusted for various vehicles without any pattern. Operators of doors and vehicles can control the height at which a door is to be adjusted and need to have clearance heights indicated to them at every adjustment.
Various attempts have heretofore been made to provide a satisfactory height indicating means. Early attempts involved attaching poles to the vehicles. An example of such a structure is shown in U.S. Pat. No. 3,137,267 issued to Hurt for a HEIGHT CLEARANCE INDICATOR. That invention involves a complex mechanism to indicate clearance by having a pole act as an antennae. Other related inventions use complex mechanisms to indicate side clearance. Examples of such mechanisms are shown in U.S. Pat. No. 3,493,925 issued to Brancale for a POSITION INDICATING SYSTEM, U.S. Pat. No. 2,706,462 issued to Evans for GARAGE DOOR GUIDES, and U.S. Pat. No. 2,569,529 issued to Kirk for a CLEARANCE INDICATOR.
None of those inventions disclose a simple height indicating system for large vehicle entry doors. It is therefore an object of the present invention to provide a safety system and method of indicating door clearance to door and vehicle operators to avoid entry door damage and risk of personal injury.
It is yet a further object of this invention to define the height of a door opening at all levels.
It is yet a further object of this invention to define safe clearance levels for specific entrance situations such as cars, people, vans or trucks.
It is yet a further object of this invention to inform an individual what a door's maximum height is and whether the door is opened to its maximum height.
It is yet a further object of this invention to allow a door to be positioned to correct heights to avoid unnecessary energy loss.
It is yet a further object of this invention to inform door operators as to the proper height to raise or lower a door.
It is yet a further object of this invention to inform vehicle operators to check door height clearance.
Objects and advantages of the present invention are set forth in part herein and part will be obvious here from, or may be learned in practice with the invention, the same being realized and attained by means of the instrumentalities and combinations pointed out in the appended claims.
The invention consists in the novel parts, constructions, arrangements, combinations, steps and improvements herein shown and described.